Halimede is one of the three tiniest moons of Neptune along with Sao
and Laomedeia. It is so small, faint, and distant, that it was
missed by the Voyager spacecraft in 1989. However, it was discovered
in 2002 by a team of astronomers using sophisticated ground based
telescope systems. It cannot be seen by the naked eye as it is 100
million times too distant and dim.

In everyday English, the word ‘eccentric’ means something or someone
that is conspicuously or grossly unconventional or unusual. In the
world of astronomy, an eccentric orbit is one that is not circular
in nature, but more elliptical. Halimede has an orbit that is
considered eccentric along with four other moons of Neptune:
Laomedeia, Psamathe, Neso, and Neried (the most eccentric of all the
moons).

Halimede also has a retrograde orbit, meaning that it orbits in the
opposite direction of Neptune’s planetary rotation. It takes a bit
over five Earth years to orbit Neptune due to the wide elliptical
nature of its orbit. At only 62 kilometers in diameter, it is
theorized that it could have once been a part of Neptune’s third
largest moon, Neried, due to its remarkably similar physical
characteristics to the larger moon. Astronomers theorize that there
is a high probability that Halimede was formed by a collision with
Neried at some point during the formation of the solar system.

Not much else is known of Halimede and her eccentric sisters, Sao
and Laomedeia; however, scientists are eager to learn more about
them. Doing so may offer insight into the planetary and cosmic
condition of our solar system during its formation billions of years
ago. Astronomers from around the world are working in a unified
effort to accomplish this important task.

Astronomer, Kuiper, named the third largest moon of Neptune, but the
second to be discovered, Nereid. A Nereid is the name used to
collectively refer to the fifty daughters of Nereus and Doris of
Greek mythology who attended to Poseidon’s, the Greek sea god, every
need. Neptune’s other moons are named following this same theme.
Other Nereids from mythology are Halimede, Laomedeia, Neso, Galatea,
Psamathe, and Sao – other moons of Neptune! Other moons of Neptune
include Naiad, a river nymph, Thalassa, Greek for ‘sea’, Larissa,
Poseidon’s lover, and Despina, the nymph daughter of Poseidon and
Demeter. The two moons named after males are the two largest,
Proteus and Triton. Both are sons of Poseidon in mythology.